On the Importance of Presuppositions

I recently had a conversation — a fairly innocuous one at the outset — which reminded me of how presuppositions can change the entire meaning of things. As I reflected on the conversation, I mentally worked on the primary thought experiment I had used in the conversation, and thought it would make a worthwhile blog post. We'll see how correct that was...

The occasion for the conversation was an interview on a Christian radio station that we were listening to in a car trip. The show's guest was a prominent apologist who was promoting his new book and taking questions from callers. I happened to disagree with much of what the guest was saying, and at times couldn't help but express my disagreement aloud — much to the chagrin of the rest of the car, I'm sure.

At the end of the broadcast, the guest made a sort of 'closing argument', in which he summarized the main point of his book. After the host signed off, I said aloud, 'By the way, don't buy his book. He's wrong.'

Someone responded, 'So you disagree with what he just said?'

'Well... not really,' I replied. 'I think he and I agree on the literal meaning of what he just said. But I know where he's coming from, and so I know that when he says what he just said, it implies different things than if I were to say the same thing.' What I meant was that our presuppositions were different, and that therefore gave different meaning to the same words and phrases.

In philosophy and apologetics, a presupposition is a belief which is foundational to a particular worldview. Usually presuppositions are axiomatic, meaning that one forms one's presuppositions without firm proof of their truth. For example, one of the most universal presuppositions is the belief that one's memory is reasonably reliable — that is, the past actually did happen and is not merely a complete fabrication of one's own mind.

The affirmation or denial of certain presuppositions can have radical worldview-altering effects. Imagine for a second if you were to presuppose that your memory was completely unreliable and that nothing actually occurred before this moment: that everything you 'remember' happening never did happen. Or imagine that the external world does not actually exist: that your life is all one big dream, and everything around you is a figment of your imagination. It would change the entire way you behave and interact with the world, wouldn't it?

One of the theological applications of the idea of presuppositions is the existence of God. Since the early 20th century, apologists and philosophers in the Reformed tradition have argued that one cannot absolutely prove or disprove the existence of God; one can only presuppose his existence or non-existence. I won't here delve into the debate over this so-called 'presuppositional apologetics', but only wish to mention its importance to modern Reformed theology.

At the time, I didn't go into a lengthy definition of 'presupposition'. Instead, I gave the following example, using simple arithmetic, which I've refined for this blog.

Below are two different presuppositions, which I've hidden in a black background. You, the reader, get to participate in this demonstration. Select one and only one of those presuppositions, and move your mouse over its corresponding black box to reveal it.

Presupposition A:   The ¤ sign signifies addition. I.e., '1 ¤ 2' is the equivalent of '1 + 2'.  

Presupposition B:   The ¤ sign signifies multiplication. I.e., '1 ¤ 2' is the equivalent of '1 × 2'.  

Now look at Equation 1 below. Given your presupposition, is the equation true?

Equation 1: 2 ¤ 2 = 4

If you have presupposed Presupposition A, you would say that Equation 1 is true, correct? If you have presupposed Presupposition B, you would also say that Equation 1 is true, correct? Now look at Equation 2 below. Is it true?

Equation 2: 2 ¤ 3 = 8

Again, regardless of whether you have presupposed A or B, you would say that Equation 2 is false. If this were all the more data we had, we might conclude that the presuppositions you hold are insignificant. After all, those who presuppose A and those who presuppose B are in 100% agreement about the truth or falsity of Equations 1 and 2! But now look at Equation 3.

Equation 3: 2 ¤ 4 = 6

If you presupposed A, you would say that Equation 3 is true. But if you presupposed B, you would say that Equation 3 is false. Despite the prior agreements, it turns out that the differences between Presuppositions A and B may actually be significant! Go ahead now and look back at the presupposition which you did not select, and you can see how the initial agreements over Equations 1 and 2 occurred.

Those who presuppose A and those who presuppose B may agree on certain statements being true or false, but they may not realize that they agree for different reasons. And while the reasons for that agreement may not have initially seemed significant, eventually the differences came to the surface. In this case, it wasn't until Equation 3 that the contrast between the two presuppositions became apparent. And now that you know what that difference is — the difference between addition and multiplication — you know how much A and B actually disagree!

Finally, suppose that someone instead holds Presupposition C, as defined below.

Presupposition C: The ¤ sign signifies an exponential. I.e., '1 ¤ 2' is the equivalent of '1²'.

Someone who presupposed C would also agree that Equation 1 is true; but he would believe Equation 2 to be true, in contrast to both A and B; and disagree with A that Equation 3 is true, but agree with B that it is false. But it should be obvious at this point that their agreements and disagreements are largely insignificant in the larger picture.¹ Even though C agrees with both A and B about the truth of Equation 1, no one would ever say that their agreement demonstrates that A, B, and C share common ground about what ¤ signifies. In reality, they all believe that ¤ signifies mutually exclusive ideas!

Jumping back to the radio show, the different presuppositions which the show's guest and I brought to the table meant that we could utter the same words — i.e., the same linguistic signs and symbols — but each intend different meanings and implications. It didn't really matter that I 'agreed' with the guest's closing statement. Because we first disagreed on some basic theological beliefs, we were also really disagreeing, even when it appeared that we agreed.

One practical example of this is the contrast between orthodox Christianity and Mormonism on the nature of God. Both religions use the word 'God' throughout their theologies; both believe that God exists in three persons; and both use the word 'Godhead' to refer to the three-parts of God.

But the orthodox Christian and Mormon conceptions of God are quite different. Orthodox Christianity is trinitarian, meaning that it believes that God is three distinct persons who coexist as one being — a paradox of unity and relationship seen as key to understanding who God is. Mormonism, on the other hand, is non-trinitarian and instead believes that God is three persons, who exist as three separate beings.

Without going too deeply into the implications of trinitarianism, suffice it to say that this nuance of difference between orthodox Christianity and Mormonism helps to partially explain many of the more apparent differences between the two religions, such as the Mormon beliefs in other gods, in the existence of the Heavenly Mother, and in the exaltation of believers to become gods themselves.

This can happen across any range of discussions, not just inter-faith ones: Does God exist? What is necessary to 'prove' something? What sources can one use for an ethical system? Can science explain that which is not observable? &c. After all, presuppositions account for some of the most fundamental beliefs by which we understand the world, much like tinted glasses.

In conclusion, I hope you take away the following: even when there is surface agreement, it is often important to be aware of where disagreements may lie underneath the surface. It is important both to understand why we both agree and disagree. While it is important that we celebrate agreement, we must also be careful that we are not also naïvely believing that agreement exists where it really does not.

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¹That is not to say that the agreements between contrasting presuppositions are entirely unimportant. In fact, sometimes the small areas of agreement can be very interesting. For example, a mathematician may be very much intrigued by the fact that 2 + 2, 2 × 2, and 2² all equal the same result.

Or put another way: brandywine, pear brandy, and apple brandy are all made from different fruit and each result in different end products. But there's a significance to the fact that all three use roughly the same process to manufacture — at least enough similarity to call all three products brandy.